Prime Minister Recep Tayyip Erdoğan denounced a video mocking Islam and the prophet Muhammad as “clear and serious provocation” and a “hostile act,” and said insulting the sacred values of Islam and its prophet cannot be justified as exercising freedom of speech.

Erdoğan, speaking at a conference in Yalta, Ukraine, also condemned a deadly attack on the US mission in Libya that killed the US ambassador and three other US diplomats, saying acts of terror and violence are “neither Islamic nor conscientious.”

US Ambassador to Libya Chris Stevens was killed in Tuesday's attack on the US Consulate in Benghazi during protests against the video, the 13-minute trailer of a movie called “Innocence of Muslims.” Sam Bacile, a man who identified himself as an Israeli Jew living in California, said he was the maker of the movie, but Bacile turned out to be a false identity and US authorities said a Coptic Christian named Nakoula Basseley Nakoula, 55, was the man behind the movie.

The movie has sparked protests and attacks on US diplomatic missions in Egypt and Yemen as well.

Erdoğan said authorities should take measures to prevent “provocations,” warning of a “cause-effect relationship” between provocative statements insulting religion and violence.

But he insisted that the right to protest cannot justify any act of terror, particularly those that harm civilians. “No one can justify acts of terror and violence, the latest example of which was the attack on the US diplomatic mission in Libya, saying that they are acting in the name of Islam,” he said. “Those who carry out such actions by exploiting Islamic rhetoric and symbols harm Muslims the most. Therefore, both those who are behind this movie and those who carry out terrorist acts should be condemned with hatred.”

The prime minister also warned the populations in Muslim countries against provocative calls for violence.

As fury against the film raged, demonstrators clashed with police near the US embassies in Egypt and Yemen on Friday. Crowds also gathered against the California-made film in Malaysia, Bangladesh and Iraq. In Nigeria, where radical Islamist sect Boko Haram has killed hundreds this year in an insurgency, the government put police on alert and stepped up security around foreign missions, while in Sudan, a mass protest was called after Muslim prayers on Friday.

“Let's please be careful on this holy Friday against any act of provocation that could result in innocent people being harmed,” Erdoğan said in Yalta.

The US and other Western embassies in Muslim countries have tightened security, fearing anger at the film may prompt attacks on their compounds after the weekly worship.

Arab Spring woes

The attack in Libya, the very country that, in the words of US Secretary of State Hillary Clinton, the US “helped liberate,” has also raised questions on the fate of “Arab Spring” revolts against authoritarian regimes across the Arab world. Syria, the latest Arab country to be shaken by the uprising, is now in a state of civil war with more than 20,000 people having been killed since protests seeking the overthrow of President Bashar al-Assad started last year.

“We called it the Arab Spring but it is no longer a spring. It is the Arab winter,” said Deputy Prime Minister Cemil Çiçek in a speech in İstanbul, voicing the growing frustration with raging violence in countries affected by the revolts.

Erdoğan, for his part, said the transformation in the Middle East is still at an early stage, asserting that “the fight for democracy cannot be won easily.”

“There will be ups and downs, there will be periods of turmoil,” he said. “The process will proceed in the direction of fulfilling legitimate demands [of the people]. In this sense, we are all witnessing the normalization of the course of the history.”

The prime minister, a staunch critic of Syrian President Assad, also dismissed what he called a “widespread but wrong perception” that developments in Syria are being masterminded by outside powers. “A people's movement in Syria has begun and spread. No power will be enough to suppress this struggle,” he said.

Concerns about Europe

In his speech, Erdoğan also expressed concern over rise of Islamophobia in Europe, where austerity measures designed to address an economic crisis are feeding xenophobia and giving a boost to far-right movements. “We are witnessing with concern that there has been a significant increase in support for far-right movements and racism is reviving in Europe, this time against Muslims,” said Erdoğan.

He said Europe should reject religious or ethnic discrimination and take measures so as not to allow the revival of “the virus of racism” that put Europe through its “darkest periods of history” in the past. “We will continue to remind our European friends of this,” he said.